Orewa Earthquake

spwill · Unread post by **spwill** » Wed 21/02/2007 21:05

Just had what I think was a small earthquake here.

NZstorm · Unread post by **NZstorm** » Wed 21/02/2007 21:10

Yes, felt that earthquake here. Just a brief tremor.

Was 3.7, depth 6km, 20km east of Orewa.

dija · Unread post by **dija** » Wed 21/02/2007 21:16

wow, not often auckland gets rattled... perhaps related to the big bang thread

somethings stirring under the top half of the north island

NZstorm · Unread post by **NZstorm** » Wed 21/02/2007 21:19

Second quake was 4.5

03Stormchaser · Unread post by **03Stormchaser** » Wed 21/02/2007 22:04

I hope you didnt spill your latte!!

dija · Unread post by **dija** » Wed 21/02/2007 23:58

be good to hear the stories from the sky tower

Andrew Massie · Unread post by **Andrew Massie** » Thu 22/02/2007 00:00

I have to admit it... that's 3 tonight now... Umm, i'm getting worried for you lot up there, NO siesmic activity for YEARS and now 3.. Some serious movement going on up there...

Manukau heads obs · Thu 22/02/2007 07:34

didnt feel it here (too sandy soil type i guess)
i see it shows on the central NI volcanic drums

3 in a row, just like the waiheke one...

the last damaging earthquake in the auckland area was port waikato.,....1880's some time?
chimneys were toppled....

Andrew Massie · Unread post by **Andrew Massie** » Thu 22/02/2007 08:13

Yeah, I have to admit, looking at geonet, it looks more volcanic than tectonic plate movement.. It's ok, guys, you've got it good! In the central South Island, we are looking at a 90% chance in the next 60 years of an 8 on the richter scale since the surface of the alpine fault hasn't moved for 250 years...

UH OH!

Manukau heads obs · Thu 22/02/2007 08:35

come to think of it, something did fall off a shelf here in the house at 9pm time...so it was felt here...now that i think about it!

spwill · Unread post by **spwill** » Thu 22/02/2007 08:38

I hope you didnt spill your latte!!

Atleast we can buy a Latte here at that time of night

A good little shake last night, thought at the time we might have been on the edge of something larger down the line as we dont get shakes here.

RODALCO · Unread post by **RODALCO** » Thu 22/02/2007 09:49

Didn't notice a thing in Titirangi.

Went to bed early to catch up to some sleep, done a lot of night work for the powerboard.

My fireservice pager went at 20.26 hrs with an earthquake alert, but even after that i didn't feel the ground shake at the later recorded timeslots, although i was asleep then.

Clay grounds around our place anyway.

squid · Unread post by **squid** » Thu 22/02/2007 13:00

that is odd to have 3 quakes in a row that far up north i wonder what is going on

Storm Struck · Unread post by **Storm Struck** » Thu 22/02/2007 19:38

What is interesting is the seismic graph at the top of the 4.5 quake it's unusual as apposed to other qaukes how it sqiggles quite large along a long duration. http://www.geonet.org.nz/2699766g.html
Suggests perhaps to me it's in the form or leading up to something due to White island activity over the last few days and Ruepahu's lahar.
It's been about a year since ive felt a good jolt.
Cheers
Jason.

C-Nimbus · Unread post by **C-Nimbus** » Fri 23/02/2007 15:26

Just thought i'd give you all some closure on this one.

Although these were shallow seated earthquakes, they are not magmatic....if they were we would experience earthquake swarms as the magma rises.

The earthquakes were on the Hauraki grabben feature, essentially s slowly sinking basin between the coromandel and the hunuas.

This fault complex heads right out to where the epicentre was so it lines up nicely.

So to put it simply this is shallow crustal movements associated with a sinking grabben (the horst features are the ranges on either side), therefore simply an adjustment to the grabben.

However this epicentre does also follow the NW trend of the auckland volcanic field which would raise alarm bells if the earthquakes were swarming and generally increasing in magitude as time went on.

What a fantastic experience though

dija · Unread post by **dija** » Fri 23/02/2007 15:46

C-Nimbus wrote:Just thought i'd give you all some closure on this one.
The earthquakes were on the Hauraki grabben feature, essentially s slowly sinking basin between the coromandel and the hunuas.

So to put it simply this is shallow crustal movements associated with a sinking grabben (the horst features are the ranges on either side), therefore simply an adjustment to the grabben.

So Auckland is sinking ??

Cool...

*joking*

Storm Struck · Unread post by **Storm Struck** » Fri 23/02/2007 21:26

Just let us know when you start sinking and we will send some life jackets up from Christchurch about 3 hours later

.
Does this mean bigger anchors or longer ropes in the harbour

.
Sounds like a good explanation there Nimbus are u a geoligist by any chance

.
Cheers
Jason.

Andrew Massie · Unread post by **Andrew Massie** » Sat 24/02/2007 07:58

Jasestrm wrote:Just let us know when you start sinking and we will send some life jackets up from Christchurch about 3 hours later .
Does this mean bigger anchors or longer ropes in the harbour .
Sounds like a good explanation there Nimbus are u a geoligist by any chance .
Cheers
Jason.

I wouldn't get too cocky there Jase.. Heard of Liquefaction? You'll need a lifejacket too if we get the big one.... Being in Kaiapoi and all! As well as me and everyone else within 2ks of the coast...

See here: http://en.wikipedia.org/wiki/Earthquake_liquefaction

NZstorm · Unread post by **NZstorm** » Sun 25/02/2007 10:58

I heard the term 'earthquake weather' mentioned on the radio last week. Does anybody really believe this? Apparently before every earthquake the weather is overcast and still!

squid · Unread post by **squid** » Sun 25/02/2007 11:32

I think there is some truth to that Nz Storm. Doesn't make much sense building a city where the land is sinking

Manukau heads obs · Sun 25/02/2007 11:43

Doesn't make much sense building a city where the land is sinking

or where the weather is always overast and still

Weather Watcher · Unread post by **Weather Watcher** » Sun 25/02/2007 13:42

Manukau heads observer wrote: ...or where the weather is always overcast and still

Doesn't Wellington disprove this theory .... lots of wind, sun and earthquakes!

RWood · Unread post by **RWood** » Sun 25/02/2007 13:52

Earthquake weather my %^&*(#$@!

Andrew Massie · Unread post by **Andrew Massie** » Sun 25/02/2007 17:51

squid wrote:I think there is some truth to that Nz Storm. Doesn't make much sense building a city where the land is sinking

Why not... look at Nagoya airport!

Manukau heads obs · Sun 25/02/2007 22:43

as they say in the states, i am just messing with you guys,LOL

re earthquake weather: its the weather you remember at the time of the earthquake....thats all, surely....its like I bet you can remember exactly what you were doing the first time you heard about 911